Okay, so let's say that you want to join the British Army but you have a beard. British Army regulations say "no beard". You can have a moustache but no beard. There are all kinds of reasons for this regulation ranging from personal discipline to cultural. You want to join the army? Here's the razor. Don't want to lose the beard? No problem, no hard feelings, see you around, close the door on the way out please. (I actually know of two people who had to face this decision btw and they both decided to shave). EDIT - As an interesting point, if you didn't want to lose the beard but still wanted to fight you could join the Royal Navy as they accept beards. Same as some koryu will accept tattoos and others won't.